几何参数对加筋圆柱壳轴压屈曲折减因子的影响

Influence of geometric parameters on the knockdown factor of the buckling of stiffened cylindrical shells under axial compression

加筋圆柱壳广泛应用于航天运载器结构中。受制造工艺影响,实际产品总是存在无法避免的几何缺陷,导致实际航天运载器结构的轴压承载力远低于理论解,需要引入一个0-1之间的折减因子乘上理论解来进行修正,令理论解在保证安全的同时尽可能接近实验值。当结构的几何参数在设计迭代过程中调整时,折减因子的值也可能会随之改变。厘清折减因子随结构几何参数发生改变时的变化规律,有助于便捷、准确地得到合适的折减因子值,从而保证结构安全、降低重量、缩短设计周期。介绍了基于边界扰动载荷法的实现过程,针对主要分析参数进行了收敛性考察,明确了分析参数的选取原则。基于该方法研究了结构的典型参数发生变化时折减因子相应的变化规律。结果表明,折减因子随蒙皮厚度的增加而线性增加,随纵筋截面面积的增加而线性减小,即蒙皮厚度越大、纵筋越是低而薄,则折减因子值越大、结构的缺陷敏感性也越低,而壳体高度的变化则对折减因子没有显著影响。

Stiffened cylindrical shells are widely used in the space vehicle structures.Due to the manufacturing process,the actual products always have unavoidable geometric imperfections,the axial compression capacity of the real structure is far lower than the theoretical buckling load,and it is necessary to introduce a knockdown factor(0-1)to correct to make the theoretical solution as close as possible to the experimental value while ensuring safety.When the structural geometric parameters are adjusted during the design iteration,the knockdown factor may be changed too.It is helpful to get the appropriate knockdown factor conveniently and accurately to clarify the change law about knockdown factor,that can ensure the structural safety,reduce the weight and shorten the design cycle.The paper introduces the implementation process of Single Boundary Perturbation Approach,and investigates the convergence of the main analysis parameters,and clarify their selection principles.Based on this method,the knockdown factor change rule is studied when parameters change.The results show that the knockdown factor increases linearly with the increase of skin thickness and decreases linearly with the increase of stringer area of section which mean the larger skin thickness and the lower and thinner stringer will reduce the structural imperfection sensitivity,and the structural height has no significant effect on the knockdown factor.